<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <form id="form1">
<p>
    <label for="tel">手机号</label>
    <input type="tel" name="tel" id="tel">
</p>
<p>
    <button type="submit">提交验证手机号</button>
</p>
    </form>
</body>
<script src="https://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.6.3.js"></script>
<script>
    $("#form1").submit(function(e){
        let tel=$("#tel").val();
        
            let reg = /^1[3456789]\d{9}$/;
            if(reg.test(tel)){
                alert("手机号合法")
            }else{
                alert("手机号不合法")
            }
            return false;
    })
</script>
</html>